This invention relates to vibrator structures, and more specifically relates to a novel electro-mechanical vibrator which can be connected to a mechanism containing a mechanical movement which will have its friction reduced by applying low periodic shock forces to the movement.
Vibrator structures or tappers are well known for use in connection with highly accurate and sensitive indicators including air data instruments such as altimeters, air speed indicators, rate of climb indicators, and the like. Typical vibrator structures for this purpose known as "tapping" devices are shown in U.S. Pat. No. 3,507,339 in the name of De Mayo, U.S. Pat. No. 3,863,114 in the name of De Mayo, and U.S. Pat. No. 3,870,103 in the name of Abel. These devices typically are relay-type vibrators and operate in the manner of a variable reluctance motor. Thus, the devices require soft magnetic material to direct the flux generated by a coil into the working air gap of the motor. This causes the armature of the motor, which carries a small hammer, to strike a hard rubber pad fixed to the housing of the device during each cycle of ocillation, thus inducing vibration required for reducing the friction of the mechanism to which the vibrator is connected.
Since the force exerted on the armature of the prior art device can be only in the direction to close the magnetic gap, the devices generally use a spring to open the gap to complete a cycle of operation.
The foregoing vibrator devices are relatively expensive to manufacture and require calibration and adjustment after assembly. The need for a mechanical spring to return the armature to its cyclic-starting position is a source of possible failure and the device characteristics are subject to change during aging and ambient temperature variations. It has also been found that there is wear of the parts due to friction between the movable armature and its guide.